Messages in this thread | | | Date | Wed, 29 Oct 2014 12:30:30 +0800 | From | Minfei Huang <> | Subject | Re: [PATCH] mm: Avoid overlap the fixmap area on i386 |
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On 10/28/14 at 08:14pm, H. Peter Anvin wrote: > On 10/28/2014 10:29 AM, Thomas Gleixner wrote: > > On Tue, 28 Oct 2014, H. Peter Anvin wrote: > >> On 10/28/2014 04:06 AM, Thomas Gleixner wrote: > >>>> > >>>> The available address we can use is lower than FIXADDR_BOOT_START. So > >>>> We will set the kmap boundary below the FIXADDR_BOOT_START, if configure > >>>> the high memory. > >>>> > >>>> If we configure the high memory, the vmalloc reserve area should end > >>>> up to PKMAP_BASE, otherwise should end up to FIXADDR_BOOT_START. > >>> > >>> Which is not really a problem, because the FIXADDR_BOOT area is only > >>> used during boot for early_ioremap() and it's unused when ioremap() is > >>> functional. vmalloc becomes available after early boot so the > >>> FIXADDR_BOOT area is available for reuse. > >>> > >> > >> Given the very limited address space available on i386, it would be > >> extremely undesirable to not reuse address space when possible. > > > > Fair enough. Then we should do that for the highmem=y case as well. > > > > It is probably even more important for highmem=y... > > -hpa
Agree. Maybe we can overlap the early_ioremap fix address to re-use it. Virtual address is more precious on i386, especially when turn on the high memory.
I will post an patch to fix it.
> >
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